Dell FCX624-S Laptop User Manual


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808 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring IP parameters – Layer 3 Switches
26
You can increase the MTU size to accommodate jumbo packet sizes up to up to 10,232 bytes in an
IronStack. Devices that are not part of an IronStack support up to 10,240 bytes.
To globally enable jumbo support on all ports of a PowerConnect device, enter commands such as
the following.
PowerConnect(config)# jumbo
PowerConnect(config)# write memory
PowerConnect(config)# end
PowerConnect# reload
Syntax: [no] jumbo
NOTE
You must save the configuration change and then reload the software to enable jumbo support.
Changing the MTU on an individual port
By default, the maximum Ethernet MTU sizes are as follows:
1500 bytes – The maximum for Ethernet II encapsulation
1492 bytes – The maximum for SNAP encapsulation
When jumbo mode is enabled, the maximum Ethernet MTU sizes are as follows:
10,240 bytes– The maximum for Ethernet II encapsulation
10,240 bytes – The maximum for SNAP encapsulation
NOTE
If you set the MTU of a port to a value lower than the global MTU and from 576 through 1499, the
port fragments the packets. However, if the port MTU is exactly 1500 and this is larger than the
global MTU, the port drops the packets.
NOTE
You must save the configuration change and then reload the software to enable jumbo support.
To change the MTU for interface 1/5 to 1000, enter the following commands.
PowerConnect(config)# interface ethernet 1/5
PowerConnect(config-if-1/5)# ip mtu 1000
PowerConnect(config-if-1/5)# write memory
PowerConnect(config-if-1/5)# end
PowerConnect# reload
Syntax: [no] ip mtu <num>
The <num> parameter specifies the MTU. Ethernet II packets can hold IP packets from 576 through
1500 bytes long. If jumbo mode is enabled, Ethernet II packets can hold IP packets up to 10,240
bytes long. Ethernet SNAP packets can hold IP packets from 576 through 1492 bytes long. If jumbo
mode is enabled, SNAP packets can hold IP packets up to 10,240 bytes long. The default MTU for
Ethernet II packets is 1500. The default MTU for SNAP packets is 1492.